The present invention relates to an ice skate, particularly for speed skating.
Conventional ice skates are generally composed of a shoe associated with a support having a longitudinal steel blade which is used as a means for gliding on a frozen surface.
In conventional ice skates the shoe support is coupled to the blade in a fixed manner, so that every movement of the foot is matched by an equal movement of the support and therefore of the blade.
However, said conventional types of skate do not allow the user to skate in an optimum manner, since they do not allow optimum transmission of efforts from the foot to the blade because for example during thrusting the front part of the blade is loaded and may therefore catch at discontinuities in the ice.
WO 96/37269 discloses a frame for ice skates comprising an upper half-frame with means for coupling to a shoe and a lower half-frame which is coupled, by means of pivoting mechanisms, to said upper half-frame for an oscillation on a main plane. The half-frames can oscillate with respect to each other and perform a translatory motion along said main plane, entailing a forward oscillation of the foot both at the tip region and at the heel region.
A schematic illustration of the movement of the foot which can be achieved with this solution is given in the accompanying FIGS. 3, 10 and 11.
As mentioned, in this solution the translatory and rotary motion of the half-frames produces a forward movement of the entire foot and therefore of both the tip and the heel; bearing in mind that the blade of the ice skate is usually radiused, in the above solution the foot performs a forward movement, loading the front part of the blade, whose primary function is not thrusting but control.
Moreover, loading the forward region of the blade makes the blade penetrate the ice and may cause jamming at other discontinuities in the ice, accordingly making the skating action less efficient.
During thrusting, the point of the blade in contact with the ice that yields the highest efficiency can in fact be determined by means of a biomechanical study of the thrusting action: this study leads to consider that the part of the blade that allows highest efficiency during thrusting is the rearmost part, as shown for example in WO 9601671, which shows that during gliding over the ice the position of the skater entails a backward-shifted position of the pelvis so that the center of gravity is arranged at the point of contact between the blade and the ice.
The result is that the tip of the blade is not in contact with the ice while the rearward part of the blade is. This allows better gliding, since friction between the blade and the ice occurs in a point corresponding to the center of gravity of the skater and therefore in a point of higher inertia.
During thrusting, the blade is arranged edgeways on the ice, assuming, by means of the backward-shifted pelvis position, that the rearward region of the blade is always the one that is interfaced with the ice: in skating biomechanics terms, the thrusting line runs through the extension of the leg along a path which is determined by the alignment of the trunk, pelvis, knee, and ankle, and the continuation of said line through the ice allows to determine the point of contact between the blade and the ice which ensures the most efficient return of energy. This means higher acceleration in relation to the energy transmitted by the skater.
The cited skates force the skater to use the front part of the blade during the last steps of the thrusting action and this entails a slight speed reduction or braking effect due to the fact that the blade tends to catch in the ice and cut a groove.
This factor is even more important when skating on natural ice, which often has many cracks and imperfections and where the above-mentioned catching therefore occurs.
Therefore, the skater runs the risk of guiding the blade into one of these grooves rather than making the blade pass beyond this obstacle, but this requires continuous trajectory corrections, wasting energy which would be useful in skating.